Research On Pressure Delivery And Co-couple Deformation Of "Compression Stockings-lower Limb" Based On Finite Element

Compression stockings also known as medical compression stockings or elastic stockings,it adopt a gradual increase pressure design,gradually reducing the pressure from the ankle up to thigh,which can effectively promote the return of venous blood to heart in lower limbs,also prevent and treat diseases such as varicose veins and thrombus.At present,scholars at home and abroad mainly focus on pressure distribution and clinical ergonomics research of compression stockings,however,its medical functional principle has not been revealed,there are few studies on pressure delivery and co-couple deformation of "compression stockings-lower limb".Firstly,a three-dimensional finite element model of "compression stockings-lower limb" was established,and the pressure distribution on surface of lower extremity model by simulation calculations is obtained.The process is introduced as follows: The limb cross-section images of lower limbs were acquired through CT scans,then a three-dimensional finite element model based on the images was established.The tensile properties and structure indexes such as size,density,and thickness of compression socks were measured,the elastic modulus and Poisson's ratio of compression socks were calculated based on the tensile test results.Then a finite element shell element model for compression stockings was setup based on above material parameters.Finally,the finite element model of "lower limb-compression stockings" was established.Through simulation calculation,the pressure distributions of lower limb under different pressure level were obtained.The comparison between simulated results and objective measured results demonstrates its practicability.Secondly,a multi-level two-dimensional finite element model based on CT images was developed.The output is the stress distribution of two-dimensional finite element section.According to the internal stress distribution of each section,combined with the analysis step of the finite element and the pressure change of each section node,the pressure delivery process was analyzed,and the pressure delivery mechanism of each section at different pressure levels is revealed.The finite element model of elastic lower limbs was established based on analysis of deformation between lower limb and compression stockings,and the actual measured pressure was applied as a static load on assembled lower limb model to obtain deformation distribution of the lower limbs under different pressure levels.This model can be used to predict deformation distribution of lower limb through comparison and verification.Finally,the co-couple deformation of "compression stockings-lower limb" was calculated and analyzed,the functional relationship between pressure and tensile-strain property of compression stockings was fitted.The displacement of points on each section was output through finite element,and the pressure and displacement are obtained as a function of pressure at point.The change and distribution of acreage and perimeter of each section under different pressure levels were obtained by division and measurement of each section of the lower limb.The results show that the perimeter and area of each section do not decrease with increasing pressure,and different sections have different variations.In the study,the target model of "compression stockings-lower limb" is simulated by finite element method the pressure distribution and stress changes of lower limb are analyzed,then the pressure delivery and co-couple deformation of "lower limbs-compression stockings" was discussed.The results and prediction model can provide references for continuing to explore functionality of pressure socks,and also provide the basis for optimal design of compression stockings.